Lift truck



Sept. 20, 1938.

A. E. WILLIAMS LIFT TRUCK Filed March 21, 1956 4 Sheets-Sheet l i lu INVENTO I AifioRNE'Y Sept 20, 1938.

4 Sheets-Sheet 2 Filed March 21, 1936 F M -i--:---:i m h k mm H h m QM x m NH u N l m m mm 6% WE-YEBM I I TORNEY Sept. 20, 1938. A. E. WILLIAMS LIFT TRUCK 4 Sheets-Sheet 3 Filed March 21, 1936 INVENTOR m 8 Q4 t I TORNEY' 1 w m. r u i 5% zwd \MM; 3. mg I IL. 4 7 M 1 2 m J WW 7 5 Z Sept. 1938. A. E, WILLIAMS 2,130,939

LIFT TRUCK Filed March 21, 1936 4 Sheets-Sheet 4 A ORNEY Patented Sept. 20, 1938 UNITED STATES PATENT OFFICE LIFT TRUCK Application March 21, 1936, Serial No. 70,024

4 Claims.

This invention relates to that class of trucks commonly called lift-trucks or elevating trucks which are used in lifting and transporting loads that are usually mounted on platforms or skids,

the truck being capable of being pushed under a skid and then raising the same on the elevating platform of the truck for transportation.

Such trucks usually include a wheeled main frame, an elevating platform mounted thereon to move vertically upon being pulled horizontally, a handle for pulling the truck, an operative connection between the handle and the elevating platform for raising the latter and a latch for holding the elevating platform in elevated position.

One object of my invention is to provide a truck of this general character embodying novel and improved features of construction whereby the handle shall be permanently operatively connected to the elevating platform so that it shall be unnecessary to manually connect and disconnect the handle from the platform, as is now common in known trucks.

Another object is to provide in such a truck 5 a novel and improved combination of a latch for holding the elevating platform in its elevated position and a locking dog for holding the latch in locking position with respect to the elevating platform, said locking dog to be automatically thrown out of locking relation to the latch by and upon swinging of the handle into a position for starting elevation of the elevating platform, whereby the possibility of the platform accidentally descending in such a manner as to suddenly throw the handle upwardly is prevented, and the locking dog may be easily and quickly thrown out of locking relation to the latch at the proper moment and with a minimum of attention by the operator.

A further object is to provide a lift truck of the general character described embodying a novel and improved construction for varying the height of the elevating platform to accommodate load carrying skids or platforms which are disposed at different distances from the floor.

Other objects are to provide in such a lift truck a novel and improved hydraulic check for retarding descent of the elevating platform and to obtain other advantages and results as will be brought out by the following description.

Referring to the drawings in which corresponding and like parts are designated throughout the several views by the same reference characters Figure 1 is a side elevation of a lift truck embodying my invention, portions being broken away and the elevating platform being shown in its lower or normal position.

Figure 2 is a top plan view of the truck.

Figure 3 is a front end elevational view thereof. 5

Figure 4 is an enlarged longitudinal vertical sectional view on the line 44 of Figure 2.

Figure 5 is a similar view showing the elevating platform in its uppermost position.

Figure 6 is a like view showing the manner of 10 throwing the locking dog out of locking relation to the latch.

Figure '7 is a transverse vertical sectional view on the line 'l'! of Figure 1.

Figure 8 is a fragmentary side elevation of the 15 rear end of the truck showing the adjustment of the elevating platform, and

Figure 9 is an enlarged fragmentary sectional elevational view of the hydraulic check.

Specifically describing the illustrated embodi- 2O merit of the invention, the reference character A designates the main frame of the truck which is mounted at its rear end on wheels I journaled on an axle 2 extending transversely in the main frame. The front end of the frame includes a 25 bolster 3 on which is journaled on the longitudinal median line of the frame, a caster 4 whereby the truck may be guided upon lateral pulls on the forward end of the frame.

An elevating platform B is mounted on the 30 main frame A by a pair of parallel links 6 at the forward end of the frame and a similar pair of links 1 at the rear end of the frame. The forward links are pivotally connected to the main frame and platform on the respective pivot pins 35 8 and 9, while the rear links I have their ends pivotally mounted respectively on the rear axle 2 and a cross rod Ill the ends of which are journaled in adjustable brackets I l which are secured to the sides of the elevating platform by bolts 40 I2 as will hereinafter more fully be described. With this construction, a forward pull on the elevating platform will result in it being raised from the main frame.

For raising the elevating platform, I have 5 shown a transverse rod i3 at the forward end of the platform to which is pivotally connected a pair of lifting links M, one at each side of the platform. The links have longitudinal slots l5 in which is slidable a cross bar l6 which connects 50 corresponding arms ll of bell crank levers 18 which are pivoted intermediate their arms on a shaft l9 at the top of the bolster, one at each side of the main frame. The other arms of the bell cranks are connected by a U-shaped handle 20. 55

The parts are so related that when the elevating platform B is in its lowermost position as shown in Figures 1 and 4, and the handle 20 is in substantially a vertical plane, the cross bar It is in the upper ends of the slots I5 of the links M and forward swinging of the handle 20 will elevate the platform as shown in Figure 5, whereupon, the platform' being held in elevated position by a latch about to be described, the handle may be freely swung about the shaft [9 without movement of the platform, the cross bar [6 riding in the slots l5.

The elevating platform is held in its uppermost position by a latch 2! which is pivotally mounted intermediate its ends on the shaft I9 and has at one end a hook 22 to engage over the rod l3 at the forward end of the platform. The other end of the latch comprises a treadle 23" for dis- A spring engaging the hook 22 from the rod I3. 24 normally influences the latch so as to bring the hook 22 in position to snap over the rod l3 when the elevating platform reaches its uppermost position, the hook end-22 of the latch having a projection 25 to facilitate riding of the hook'over the rod l 3.

To prevent accidental disengagement of the latch from the rod l 3 in such a manner as to allow the platform to suddenly descend under the weight thereon and cause possible injury to the operator by sudden upswinging of the handle 20, I have provided a locking dog 25 which is pivotally mounted at one end at 27 on a standard 28 at the forward end of the elevating platform, the dog overlying the rod l3 as shown in Figures 4 and 5. The dog is held in this position by action of gravity and is so spaced from the rod 53 that,

the hook 22 may swing the dog rearwardly and then snap over the rod l3 when the plat-form B reaches its uppermost position. The dog then swings by gravity into a position over the hook 22 and is so spaced from the hook as to prevent swinging of the hook upwardly sufficiently to disengage the hook from the rod l3, as shown in Figure 5.

The dog 25 is automatically thrown out of such locking position as the handle 20 is raised, by engagement of the dog by the cross bar it which connects the bell cranks l8 as shown in Figure 6, whereupon the latch may be disconnected from the rod l3 and the. platform may be released for descent. It will be noted however, that at this time the handle is in substantially its uppermost vertical position with the cross rod H5 at the inner ends of the slots l5 in the lifting links it so that the descent of the platform will not have any eifect upon swinging of the handle. All danger to the operator is thereby eliminated. When. the handle is again swung downwardly the dog will swing into its normal locking position by action of gravity as shown in Figure 4.

Another feature of the invention is an adjustable mounting of the elevating platform B. As shown, the forward parallel links 6 are connected to the standard 28, and the side pieces 29 of the elevating platform are bolted at 30 to the standard. The standard hasa plurality of vertically spaced openings 3i so that the side pieces 29 can be connected to' the standard at different elevations. I n

The rear end of the elevating platform carries the brackets l l which have two pairs of openings 3i spaced different distances from the point of journaling of the rod IS in the brackets. .Accordingly when the brackets are connected to the side pieces of the elevating platform with the disposed at a higher elevation as shown in Figure 8.

Lift trucks of this general character usually include a hydraulic check for retarding descent of the elevating platform and my invention contemplates a novel and improved check. As shown in the drawings, the check includes a cylinder 32 pivotally mounted at one end 33 on the rear axle 2 and havinga piston, 3 reciprocable therein which has a piston ,rod 35 pivotally connected at 36 to the standard 28 on the elevating platform. The piston comprises two plates 36 which are riveted together and clamp between them a cup packing washer 31 to engage the inner walls of the cylinder and facing in the direction of movement of the piston as the'platforrn descends. The piston has a limited sliding" movement'on the rod 35, movement being limited in one direction by a collar 38 and being limited in the other direction by nuts 39. The inner end of the piston rod has a longitudinal groove 40 leading beneath the nuts 39 and the piston 36 to the .collar 38 and the collar has a packing washer M to be abuttedby the piston. The cylinder is filled with liquid such as oil, and when the platform B is elevated, the piston rod-moves to the left of Figures 1 and 9 and the piston during-the initial movementof the rod slides into engagement with the nuts 39 so as to permit the oil to flow through the groove 40. Some oil will also flow around the edges of the packing washer 31. When the elevating platform descends, the rod 35 moves in the opposite direction and upon initial movement the piston 34 slides against the packing washer 4! to close the groove-40, and the packing wall to preventthe flo-wof oil past the piston.

Descent of the elevating platform is thereby retarded, but to permit slow movement of the platform, the pistonhas a leak port 42 which allows the oil to flow slowly from one end of the cylinder to the otherin such a manner as to allow descent of the platform but at a slow rate.

' Obviously the truck may be moved from place to place by pulling on the handle 20, lateral pulls causing the forward end of the truck to swing on the caster 4 to permit steering of the truck.

While I have shown and described the inven' tion as embodied in certain details of construction it'should be understood that this is primarily for the purpose of illustrating the principles of the invention and that the details of structure may be modified by those skilled in the art without departing from the spirit or scope of the claims; 7

Having thus described my invention, what I claim is: r r

V 1. An elevating truck comprisinga wheeledv main frame, an elevating platform mounted on said main frame for movement vertically upon being pulled forwardly, a pair of links pivoted at one end on said platform, one at each side thereof and having an elongated slot, and a handle having a pair of rigidly connected bell cranks pivoted to rotate about a horizontal axis on, and one ateach side of, said main frame, and a, cross rod connectingcorresponding arms of said bell cranks and slidable in said slots so that said platform can be elevated by swinging of said handle downwardly in one direction and engagement of the outer ends of said slots by said cross rod, and after elevation of the platform said handle may be swung upwardly and said cross, rod may slide toward the other ends of said slots to permit the platform to descend with said links sliding idly over said cross rod without effecting movement of the handle, and means for releasably locking said platform in elevated position.

2. An elevating truck comprising a wheeled main frame, an elevating platform including side pieces and a standard connected to said side pieces at one end, a bracket secured to each side piece adjacent the rear end thereof, a shaft journaled in said brackets, a pair of parallel lifting links pivotally connected at one end to said shaft and at their other ends to the main frame, a second pair of parallel links pivotally connected at one end to said standard and at their other ends to said main frame, means adjustably mounting said brackets on said side pieces and means adjustably mounting the side pieces vertically on said standard to vary the height of the elevating platform.

3. An elevating truck comprising a wheeled main frame, an elevating platform including side pieces and a standard connected to said side pieces at one end, a bracket secured to each side piece adjacent the rear end thereof, a shaft journaled in said brackets, a pair of parallel lifting links pivotally connected at one end to said shaft and at their other ends to the main frame, a second pair of parallel links pivotally connected at one end to said standard and at their other ends to said main frame, each side piece having a set of bolt openings and each bracket having a plurality of sets of bolt openings spaced different distances from the point of journaling of said shaft in said brackets to selectively cooperate with said sets of openings in the side pieces to receive bolts for connecting the brackets to the side pieces in different positions and vary the height of the platform, said standard having a plurality of sets of bolt holes at each side and each side piece having a set of bolt holes to selectively cooperate with said sets of holes in the standard and receive bolts for connecting said side pieces to said standard at different heights. 4. An elevating truck comprising a wheeled main frame, an elevating platform mounted on said main frame for movement vertically upon being pulled" forwardly, a pair of links each pivoted at one end on said platform at one side thereof and having an elongated slot adjacent its other end, and a handle having a pair of rigidly connected bell cranks pivoted to rotate on a horizontal axis on said main frame and a cross rod connecting corresponding arms of said bell cranks and slidable in said slots in the links so that said platform can be elevated by swinging of said handle downwardly in one direction and engagement of the outer ends of said slots by said cross rod, and after elevation of the platform said handle may be swung upwardly and said cross rod may slide toward the other ends of said slots to permit the platform to descend without affecting movement of the handle, a latch on said main frame to engage a part on said platform for holding said platform in elevated position, a locking dog on said platform actuated by gravity into position to lock said latch in holding position when the platform is elevated, said dog being located on the platform so that when the platform is locked in elevated position the dog is directly engaged by said cross rod of the handle as the'handle is swung upwardly and reaches the position for beginning elevation of the platform.

ARTHUR E. WILLIAMS. 

